The above type of switch is disclosed for example in French patent specification No. 95 10566 of the Company Valeo Electronique. It is generally used for the control of an electrical apparatus such as the electric motor of a blower. The primary contact strips in the set are connected to load resistors having different values. Thus, a user can set the running mode, or speed, of the motor of the installation according to the contacts established by the switch, and in consequence according to its angular position. This setting governs the mass flow of air processed in the installation that is delivered into the cabin of the vehicle.
Because of its configuration, such a switch is of an overall size, especially in the radial direction, which is such as to confine its use to certain types of vehicles. In addition, its relatively large overall size prevents the installation from being controlled in different operating modes, of which there are at least two.